Recently, medical images previously interpreted to make diagnoses and information related to the results of the image interpretations and the results of the diagnoses are actively stored in databases for the purposes of helping radiologists to interpret medical images and helping clinicians to make diagnoses. Furthermore, similar case search systems have been proposed which are intended to search out, from the databases, medical images similar to target medical images to be interpreted by doctors to make diagnoses and the information related to the results of interpreting the medical images and the results of the diagnoses.
In such a conventional similar case search system, a database stores a large number of document data sets (hereinafter referred to as “image interpretation reports”) related to the results of image interpretations and diagnoses. In this case, the database is searched for image interpretation reports including character strings (words) similar to character strings included in an image interpretation report (hereinafter referred to as a “current image interpretation report”) input by a doctor. As a result, the searched-out similar image interpretation report and the medical images associated with the similar image interpretation report are output as the result of the search (see Non-patent Literature (NPL) 1).
In such a conventional case search system, the image interpretation report is searched out using a vector having, as an element, the total number of keywords included in the image interpretation report. More specifically, the degree of similarity of each image interpretation report in the database with respect to a current image interpretation report is calculated by calculating the distance between the vector of the image interpretation report in the database and the vector of the current image interpretation report. In the search, image interpretation reports found to have a higher similarity are preferentially searched out.